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Protein · Answer
Whey digests faster and suits any time of day; casein digests over several hours and is mainly useful as a 30–40 g pre-sleep dose (ISSN). For muscle gain over weeks, total daily protein matters more than type. In South Africa whey is easier to find and often cheaper: casein tubs cost R500–R1 200, mainstream whey R330–R700 (October 2026).
Both are complete milk proteins that build muscle. Whey is a fast-digesting liquid fraction rich in leucine. Casein forms a gel in the stomach and releases amino acids over several hours. The ISSN treats casein mainly as a pre-sleep option and whey as the convenient all-round protein.
| Whey | Casein | |
|---|---|---|
| Digestion | fast | slow, several hours |
| Leucine per gram of protein | higher (about 10–11%) | lower |
| Best use | after training, with meals, anytime | before sleep, long gaps between meals |
| Availability in South Africa | wide: 61 whey products on Dis-Chem's sports store | thin: 7 on Dis-Chem's sports store |
| Typical tub price (October 2026) | R329–R700 local; R1 150–R1 300 imported | R500–R1 200 |
| Evidence level | strong | moderate |
No. Over weeks, total daily protein and training drive results, not the protein type. Where casein earns its place is the pre-sleep window: Res and colleagues (2012) found 40 g of casein before sleep after evening exercise improved overnight protein balance, and the ISSN reports 30–40 g raises overnight muscle protein synthesis without impairing fat burning. You can also get a useful overnight effect from a glass of milk, yoghurt or cottage cheese.
At NPL the two are close: Casein Slow Release 750 g at R629.99 is about R34 per 30 g of protein, against about R33 for NPL Platinum Whey 908 g. Elsewhere, whey is cheaper: USN BlueLab 1 kg is about R28 and NPL Platinum Whey Plus about R23.50 per 30 g of protein. Casein tubs from Primal and Nutritech (about R500) look cheap per 100 g of powder, but without published protein per serving we cannot compare protein cost. See the best casein protein and per 30 g protein comparison answers.
Milk allergy rules out both. If you have kidney disease, are pregnant or under 18, ask a doctor or dietitian before raising protein. For timing guidance see when to take whey, and for product picks the best whey protein in South Africa page.
| Product | Size | Price (source, date) | Servings | R per 30 g protein | R per 100 g powder | Sweeteners |
|---|---|---|---|---|---|---|
| NPL Casein Slow Release Night Time Protein (750 g) | 750 g | R589.99-R629.99 (Dis-Chem Living Fit, 2026-10) | — | R34.36 | R84.00 | sucralose |
| NPL Platinum Whey (908 g) | 908 g | R700 (NPL shop (npl.za.com), 2026-10) | — | R32.89 | R77.09 | sucralose |
| USN BlueLab 100% Whey Protein (1 kg) | 1 kg | R689 (USN shop (za.usn.global), 2026-10) | — | R28.03 | R68.90 | not stated |
| Primal Casein Protein (750 g) | 750 g | R500 (Dis-Chem Living Fit, 2026-10) | — | — | R66.67 | sucralose |
| Optimum Nutrition Gold Standard 100% Casein (900 g) | 900 g | R1 200 (Dis-Chem Living Fit, 2026-10) | — | — | R133.33 | not stated |
Educational information, not medical advice. Speak to a doctor, pharmacist or registered dietitian before using supplements if you are pregnant or breastfeeding, under 18, taking medication, or living with kidney, liver or heart disease. Prices were observed in October 2026 and are not offers.